5-trifluoromethyl-7-aminobenzimidazoles

ABSTRACT

Benzimidazoles having 5-trifluoromethyl and 7-amino substituents are useful as herbicides. The 1-and 2-positions of the molecule also have at least one substituent; and, preferably both positions are substituted, such as with alkyl groups.

United States Patent Hunter et al.

[ Aug. 26, 1975 5-TRIFLUOROMETHYL-7- AMINOBENZIMIDAZOLES Inventors: Don L. Hunter; Robert A. Smith,

both of Anaheim; Wayne S. Belles, Orange, all of Calif.

Assignee: United States Borax & Chemical Corporation, Los Angeles, Calif.

Filed: June 3, 1974 Appl. No.1 476,018

Related U.S. Application Data Continuation-impart of Ser. No. 333,902, Feb. 20,

i973, abandoned.

U.S. Cl. 260/309.2; 71/92; 260/569; 260/575; 260/577; 260/578; 260/580 Int. Cl C07d 49/38 [58] Field of Search 260/309.2

References Cited FOREIGN PATENTS OR APPLICATIONS Li I 1,905 5/1968 United Kingdom 260/309.2

Primary Examiner-Natalie Trousof Attorney, Agent, or Firm-James R. Thornton [57] ABSTRACT 14 Claims, No Drawings 5-TRlFLUOROMETHYL-7- AMINOBENZIMIDAZOLES This is a continuation-in-part of our copending application Ser. No. 333.902 filed Feb. 20. I973. now abandoned.

This invention relates to a novel class of substituted benzimidazoles and. more particularly. to a class of 5- trifluoromethyl-laminobenzimidazoles having utility as herbicides. The novel benzimidazo'les of this invention have the formula i CF3 C-R2 u Further. not more than one of R and R represents hydrogen and not more than one of X and X represents Thus. the benzimidazoles have at least one amino group at the 7-position which may be unsubstituted or which may have one or two lower alkyl substituents. The present compounds must also have a trifluoromethyl group at the 5-position of the benzimidazole molecule. Other possible substituents include the halogens such as bromo, chloro. iodo and fluoro; lower alkoxy of l to about 6 carbon atoms such as methoxy. ethoxy. n-butoxy and n-hexyloxy; and an additional amino group which may be unsubstituted or which may have one or two lower alkyl substituents as defined by R R and R can each represent a lower alkyl or lower cycloalkyl substituent which may contain from 1 to about 6 carbon atoms and. optionally. may have one or more halo. hydroxy or lower alkoxy substituents. Examples of such groups include methyl. ethyl. n-propyl. isopropyl. sec-butyl. 3-pentyl. cyclopropyl. cyclobutyl. cyclohcxyl. n-hexyl. Z-bromoethyl. 3-chloropropyl. 2- hydroxyethyl. 2-chlorocyclohexyl. B-hydroxypropyl. chloromethyl. methoxymethyl. 3-ethoxypropyl. 2.2 dichloroethyl, Z-methoxyethyl. l-methyl-2 methoxyethyl. 2.2-dilluoroethyl. 2.2-diethxyethyl. 4- hydroxybutyl, and the like. In a preferred embodiment.

2 the hydrocarbon substituents represented by R, R contain a total of 2 to about 6 carbon atoms. Alternatively. R and R may represent a di-lower alkylamino group and R can represent a halo group. especially bromo or chloro. as defined above.

The lor 2-positions of the benzimidazole molecule may be unsubstituted; however, at least one. and preferably both, of the land 2-positions are substituted. Examples of compounds embraced by the formula above include those in which X. is hydrogen and X is chloro, and those in which both R 's in the 7amino group are hydrogen. The compounds may also be in the salt form such as the hydrochloride. Representative compounds. according to the present invention include:

7-amino-2-ethyl-5-trifluoromethylbenzimidazole 7-amino-2-rnethyl-6-chloro-5- trifluoromethylbenzimidazole 7-amino-2-isopropyl-6-methoxy5- trifluoromethylbenzimidazole 7-ethylaminol -ethyl-2methyl-5- trifluoromethylbenzimidazole 7-amino-l-ethyl-2-methyl-6-fluor0-5- trifluoromethylbenzimidazole 6,7-diamino-l-see-butyl-Zethyl-S- trifluoromethylbenzimidazole 7-dimethylamino-2-isopropyl-6-bromo-S- trifluoromethylbenzimidazole 7-amino-2-n-hexyl-5-trifluoromethylbenzimidazole 7-amino-4-chloro-2-ethyl-5 trifluoromethylbenzimidazole 7-methylaminol -methyl-2-sec-butyl-6-ethoxy-5- trifluoromethylbenzimidazole 7-amino-2-chloro-S-trifluoromethylbenzimidazole 7-amino-2-(dimethylamino)-l-isopropyl-6-chloro-5- trifluoromethylbenzimidazole 7-amino-l-ethyl-2-(2-hydroxyethyl)-6-methoxy-5- trifluoromethylbenzimidazole 7-amin0- l -isopropyl-2bromo-6-meth0xy-5- trifluoromethylbenzimidazole 7-aminol l-methyl-2-methoxyethyl)-2-ethyl-5- trifluoromethylbenzimidazole 7-aminol -ethyl-6'methoxy-2-methyl-S- trifluoromethylbenzimidazole 7-aminol -ethyl-6-chloro-2-methyl-5- trifluoromethylbenzimidazole 7-amino-6-dimethylaminol-ethyl-2-methyl-5- trifluoromethylbenzimidazole 7-amino-6-chlorol -cyclopropyl-2-methyl-5- trifluoromethylbenzimidazole 7-amino-l-ethyl-2-methyl-5- trifluoromethylbenzimidazole 4.7-diamino-6-chlorol -ethyl-2-isopropyl-5- trifluoromethylbenzimidazole 7-amino-4,6-dichlorol -ethyl-2-methyl-5- trifluoromethylbenzimidazole 7-amino-6-chlorol -isopropyl-5- trifluoromethylbenzimidazole 7-amino-l-ethyl-2-(methoxymethyl)-6-bromo-5- trifluoromethylbenzimidazole 7-amino-l-methyl-2-(diethylamino)-6 chloro-5- trifluoromethylbenzimidazole The compounds of this invention are generally crystalline solids. being soluble in organic solvents such as alcohol, acetone. the chlorinated hydrocarbons. benzene. etc. They are readily prepared by procedures known for the preparation of benzimidazoles such as the reaction of the corresponding substituted 0- phenylenediamine with a carhoxylic acid in the presence ofa mineral acid according to the following equation R2COOH C-R2 EH in which R' is lower alkyl such as ethyl. and are generally used in their hydrochloride form. A suitable synthesis is illustrated as follows:

ZFV N0 [H] 40 NHR F3\/ N'H2 fir c Q RZCOR' NHR H 'lhc phosgencimmonium salt has the formula (l !/R v t N (I (l R in which R is lower alkyl and a suitable synthesis is illustrated by the equation:

In many cases such as when the 6-position is substituted it may be more convenient to prepare the 7- nitrobenzimidazole and then reduce the nitro group to an amino group such as with hydrogen in the presence of a catalyst such as platinum oxide. The nitro group may be present on the ortho-phenylenediamine prior to its conversion to the benzimidazole or. alternatively a benzimidazole free ofa 7-substituted may be nitrated such as with nitric acid, to give the 7-nitro derivative, which is then reduced to the desired 7-amino derivative. A suitable synthesis is illustrated as follows.

i CF G [H] x NHR 4 CF NH2 )q/ NHR t CF N -R2 BN0 X6 N X N 0F u CF3 N 9 H X N [H] N CF o X6 N When R is a halo group, the 7nitrobenzimidazole compound can be prepared by halogenation of the corresponding benzimidazolone such as with the phosphorus oxychloride or phosphorus oxybromide. such as illustrated below. and then nitration of the resultant 2- halobcnzimidazole.

CF NH 0 eocr a X24 I N CF.

czo x H X I CF P00 1 J 0 9:0 ac 1 X 1 N CF3 JP 0 -c1 X6 1 See British Patent Specification No. [298,020 which describes preparation of 2.6-dinitro-3-halo4- trifluoromethylanilines by reaction of a 2,4-dihalo-3.S- dinitrobenzotrifluoride with an amine. The halo group can be replaced by an alkoxy or amino group by known procedures, if desired. See also US. Patent No. 3,466.329 which shows the chemical reduction of 2.6- dinitro-4-trifluoromethylanilines employing sodium sulfide to produce the corresponding 6-nitro-4- trifluoromethyl-l ,Z-phenylenediamine.

The preparation of Z-dialkylamino-S- trifluoromethyl-7-nitrobenzimidazole compounds by reaction of an o-phenylenediamine with a phosgeneimmonium chloride is disclosed and claimed in a copending application of Kelvin Kei-wei Shen. Ser. No. 556,076 filed Mar. 10,1975, assigned to the assignee of the present application.

The following examples illustrate the preparation of representative compounds of this invention and intermediates thereforv EXAMPLE I N-Ethyl-3-chloro-6-nitro-4-trifluoromethylaniline Aqueous ethylamine 29.72g.; 0.46 mole) was added to a stirred solution of 60g. (0.23 mole) of 2,4- diehloro-S-nitrobenzotrifluoride in 200 ml. of dimethoxyethane. The mixture was stirred for 2 hours while the exotherm subsided and then heated near reflux temperature overnight. The resulting mixture was evaporated to dryness at reduced pressure and the residue dissolved in chloroform. After washing twice with water, the chloroform solution was dried over sodium sulfate, filtered. and the solvent removed from the filtrate by distillation under reduced pressure. Crystallization of the residue from ethanol gave 57.0g. (871% of N-ethyl-3-chloro-6-nitro-4- trifluoromethylaniline, m.p. 92.594.

EXAMPLE I1 o-Chlorol -ethyl-2-methyl-5- trifluoromethylbenzimidazole A hydrogenation bottle was charged with 289g. (0.l075 mole) of N ethyl-3-chloro-6-nitro-4 trifluoromethylaniline, 0.2g. of platinum oxide catalyst. and 300 ml. of ethyl acetate Shaking for 20.5 hours under 50 psi pressure resulted in the uptake of 3.18

7 mole equivalents (98.6%) of hydrogen. The catalyst was removed by filtration and the solvent evaporated from the filtrate. The resulting solid was dissolved in 200 ml. of ethanol and 14.62g. (0.12 mole) of ethyl methylcarboximidate hydrochloride added. After 48 hours at room temperature. the solvent was removed and the residue dissolved in chloroform and filtered. Removal of the chloroform by distillation followed by recrystallization ofthe residue from hexane gave 203g. (71.9%) of the product as yellow-red crystals. m.p. 1 18l 19C.

EXAMPLE Ill 6-Chloro-1-ethyl-2-methyl-7-nitro-5- trit'luoromethylbenzimidazole To a solution of 11.0g. (0.04 mole) of 6-chloro-lethyl-2-methyl-5-trifluoromethylbenzimidazole dissolved in 110 ml. of concentrated sulfuric acid was added 1 1 ml. of 90% fuming nitric acid while cooling with an ice bath. The addition required 3 hours and the resulting red-brown solution was stirred for 6 hours at C. and then at room temperature for 2.5 days. After pouring onto ice. the product was precipitated by the addition of 350 ml. of concentrated ammonium hydroxide. The crude solid was isolated and dissolved in 300 ml. of chloroform. The chloroform solution was washed with water, dried over Na SO filtered, and the filtrate evaporated. Crystallization of the residual solid from hexaneCCl., (3:1) gave 9.0g. (70%) of reddish solid. mp. 1 l4-116C., whose nuclear magnetic resonance pattern confirmed it to be the desired product.

EXAMPLE IV 7-Amino-6-chloro- 1 -ethyl-2-methyl-5- trifluoromethylbcnzimidazole About 5g. (0.0166 mole) of 6-chloro-1-ethyl-2- methyl-7-nitro-5-trifluoromethylbenzimidazole was hydrogenated in 100 ml. of methanol in the presence of 0. g. of platinum oxide. The theoretical amount of hydrogen was absorbed in 4 hours of shaking. After filtration and removal of the methanol, the crude product was crystallized from carbon tetrachloride to give 2.3g. (51%) of reddish brown solid, mp. l76-178C. An nmr spectrum confirmed the structure as 7-amino-6- chloro-l-ethyl-Z-methyl-S- trifluoromethylbenzimidazole.

EXAMPLE V N-Ethyl-3-mcthoxy-o-nitro-4-trifluoromethylaniline A solution of 14.0g. (0.052 mole) of N-cthyl-3- chloro-o-nitro-4-trifluoromethylaniline and 16.98g. (0.057 mole) of 18.23% methanolic sodium methoxide in ml. of anhydrous methanol was sealed in a glass tube and heated at l 19C. for 88 hours. Removal of the solvent by distillation left a yellow solid residue which was triturated with hot chloroform. Filtration and evaporation of chloroform from the filtrate gave a crude solid residue. Crystallization of the residue from ethanol gave 124g. of yellow crystalline product. mp. l40.5l41.5(. shown by its nmr spectrum to be the iesired methoxyaniline.

EXAMPLE vi 1-Ethyl-t -methoxyJ-mcthyl-S- trilluoromcthylbcnzimidazole A solution of 244g. (0.09 mole) of N cthyl-3- methoxy-(rnitro-4-trif'luoromethylaniline in 200 ml. of ethyl acetate, plus 100 ml. of ethanol. was hydrogenated in the presence 01 0.2g. of platinum oxide at room temperature. The theoretical amount of hydrogen was absorbed in 19 hours of shaking at 60 psi. The catalyst was removed by filtration and the solvent evap orated at reduced pressure. The solid residue was dissolved in 200 ml. of absolute ethanol and 12.58g. (0.10 mole) of ethyl methylcarboximidate hydrochloride added. The mixture was stirred overnight at room temperature and the solvent removed at reduced pressure. Trituration of the brown residue with 200 ml. of chloroform, filtration, and evaporation of solvent from the filtrate left the crude residual product. Crystallization from hexane-CCL, (3:1) gave 18.1g. (76%) of brown. shiny needles. Recrystallization from hexane gave the pure product, m.p. l27129.5C. whose structure was confirmed by an nmr spectrum.

EXAMPLE VII 1-Ethy1-6-methoxy-2-methyl-7 -nitro-5-trifluoromethylbenzimidazole l-Ethyl-6-methoxy-2-methyl-5- trifluoromethylbenzimidazole 1-Ethyl-6-methoxy-2-methyl-5- trifluoromethylbenzimidazole (1 1.0g; 0.04 mole) was added in portions over 3 hours to a cooled mixture of l 10 ml. of concentrated sulfuric acid and l 1 ml. of% white fuming nitric acid. The resulting brown solution was held at 0C. for 6 hours and then at 25C for 3 days. Addition to ice water follwed by neutralization with 350 ml. of concentrated aqueous ammonia gave a brown. oily precipitate. The product was extracted thrice with 100 ml. ofchloroform, the extracts washed with water, dried over Na SO filtered, and the chloroform removed by distillation. The residue was crystallized from 3:1 hexane-CCl. to give 5.5g. (42.7%) of yellow solid. Recrystallization from hexane gave the desired product, m.p. 8485.5C.

EXAMPLE V111 7-Aminol -ethyl-6-methoxy2-methyl-5' trifluoromethylbenzimidazole l-Ethyl-6-methoxy-2-methyl-7-nitro-5- trifluoromethylbenzimidazole (3.88g.; 0.01 mole) in 50 ml. of ethyl acetate was hydrogenated in the presence of 0.1g. of platinum oxide catalyst. Shaking for 20.5 hours at room temperature resulted in the uptake of 80% of the amount of hydrogen needed to reduce the nitro group. Filtration to remove the catalyst was followed by solvent removal and trituration with hot CCl The hot CCl solution was filtered and the solvent evaporated at reduced pressure leaving 3.3g. of solid product. Two recrystallizations from CCl gave the pure product, m.p. 17l.5174.5C.

EXAMPLE 1X 7-Amino-1-ethyl-2-methyl-5- trifluoromethylbenzimidazole N-EthyL2.6-dinitro-4-trifluoromethylaniline was bydrogenated in 200 ml. of ethyl acetate in the presence of tllSg. of platinum oxide catalyst. One hour ofshalxing was sufficient for the absorption of enough hydrogen to reduce both nitro groups. The catalyst was removed by filtration and the ethyl acetate evaporated leaving an orange viscous residue. The latter was dissolved in 100 ml. of ethanol and 4.87g. (0.04 mole) of ethyl methylcarboxiniidate hydrochloride added. This mixture was stirred at room temperature for 16 hours. the solvent removed. and the residue triturated with 250 ml. of chloroform. Filtration and removal of the chloroform left a crude solid that was crystallized from CCI to give 6.66g. (76.5%) of product. m.p. l43.5t45C. An nmr spectrum was consistent with the stureture of 7-amino-l-ethyl-2-methyl-5- trifluoromethylbenzimidazole. After recrystallization from CCI the product melts at l3l132C.

EXAMPLE X 7-Amino-6-bromol -ethyl-2-methyl-5- trifluoromethylbenzimidazole 7-Amino-l-ethyl-2-methyl-5- trifluoromethylbenzimidazole (0.8g; 3.3 moles) was dissolved in 15 ml. of acetic acid. To this solution, bromine (0.525g.; 3.3 moles) dissolved in 10 ml. of acetic acid, was added drop-wise with stirring and cooling. The solution was stirred for one hour after the addition was completed. and then poured into ice-water. The mixture was neutralized with aqueous sodium hydroxide and extracted twice with I ml. of chloroform. The chloroform was evaporated to dryness and the residue found to be a mixture of 7-amino-6 bromo-l-ethyl- 2-methyl-5-trifluoromethylbenzimidazole and the corresponding 4-br0mo isomer. The more soluble 6- bromo isomer was separated by digestion in 30 ml. of chloroform. The crystalline 6-hromo isomer was obtained in 36% yield; m.p. l7l-l74C.

EXAMPLE XI 6Chlorol -ethyl 2-methyI-7-methylamino-S- trifluoromethylbenzimidazole To 1.0g. of 7-amino6-chloro-l-ethyl-2-methyl-5- trifluoromethylbenzimidazole (Example IV) dissolved in I0 ml. of concentrated H SO was added 1.0g. of paraformaldehyde. The resultant mixture was stirred at 80C. for 2 hours and then poured onto ice. The resul' tant brown solution was made basic by addition of eon eentrated NH OH. precipitating a light brown solid. The mixture was extracted with chloroform and the chloroform extracts washed with water and dried over Na SO After removal of the chloroform by evaporation, the residue was extracted with hexane and the hexane extract distilled to dryness. The solid residue was recrystallized from hexane to give 0.77g. (73.3%) of the desired product. m.p. I l6.5-l 19C.

EXAMPLE XII 7-Amino-6-chlorol -ethyl-- trifl uoromethylbcnzimidazole h-Chloro-I-ethyl-7-nitro-5- trifluoromethylbenzimidazole (3.54g.; 0.012 mole; mp l26.5-l28C.) was hydrogenated in the presence of platinum oxide catalyst in accordance with the pro cedure of Example IV. The product was obtained as a white crystalline solid l.54g.; 48.9%) which. after re crystallization from a CCI (.'HCI; mixture. melts at l9].5-I93C.

EXAMPLE XIII 6Dimethylamino l -ethyl-2-methyl-7-nitro-5 trilluoromethylbenzimidazole A glass reaction tube was charged with 5.0g. (0.0l6 mole) of fi-chloro-l -ethyl-2-methyl7-nitro-5 trifluoromethylbenzimidazole. 20 ml. of dimethoxyethane and I5 ml. of dimethylamine and then sealed. The sealed tube was maintained at I25C. for 16 days and then opened. The contents were evaporated to dryness and the residue extracted with hot hexane, from which crystallized 3.1g. of the desired product m.p. l l ll 15C. after recrystallization from hexane.

EXAMPLE XIV 7-Amino-6-dimethylamino-l -ethyl-2-methyl 5trif'luoromethylbenzimidazole o-Dimethylamino-l-ethyl-2-methyl-7-nitro-5- trifluoromethylbenzimidazole (1.5g) was hydrogenated in the presence of platinum oxide catalyst according to the procedure of Example IV to give 083g. of the desired product. m.p. I4Il42 C.

EXAMPLE XV 7Amino-2.6-dichloro- 1 -ethyl5- trifluoromethylbenzimidazole EXAMPLE XVI 7-Amino-6-chloro' I dimethylamino )-2-methyl-5 trifluoromethylbenzimidazole A solution of 5.2g. of N -(dimethylamino) 4-chloro- 3-nitro-5-trifluoromethyl-I.Z-phenylenediamine (prepared by hydrogenation of the corresponding 3.5- dinitro-4-hydrazinobenzotrifluoride in the presence of palladium catalyst) and 7.5g. ofethyl methylcarboximidate hydrochloride in ml. of ethanol was refluxed for 26 hours. The resultant 7-nitrobenzimidazole was separated by fractionation on a silica gel column and then hydrogenated in the presence of platinum oxide catalyst in dimethoxyethane-methanol to give the desired product (2.8g) m.p. l73-I74C.

EXAMPLE XVII 7'Amino-6-chloro- I Z-hydroxyethyl )-5 trifluoromethylbcnzimidazole A mixture of 0.5g. of 4-chloro-N -(B-hydroxyethyl)- 3-riitro-5-trifluoromethyll ,2-phenylenediamine and 05g. of formic acid was refluxed in 40 ml. of 4N hydrochloric acid for 24 hours. The resultant mixture was neutralized with ammonium hydroxide, extracted with chloroform, dried and then evaporated to dryness. The resultant nitro-benzimidazole melts at l47l 50C. after recrystallization from chloroform. It was hydrogenated in the presence of PtO, to give the desired 7- aminobenzimidazole. m.p. 235236C.

EXAMPLE XVIII 7Amino-6-chloro-2( dimethylamino l -ethyltrifluoromethylbenzimidazole To a solution of 286g. of 4-chloro-N -ethyl-3-nitro- S-trifluoromethyl-l,2-phenylenediamine in 120 ml. of chloroform was added, slowly, 2.50g. of N.N- dimethylphosgeneimmonium chloride with stirring. After the addition was completed, the resultant mixture was refluxed for 3 days and then poured into an icewater mixture. After neutralization with sodium hydroxide, the organic phase was separated, dried and evaporated to dryness. The solid residue was washed with nhexane-ether mixture to leave 1.0g. of yellow :rystalline nitrobenzimidazole, m.p. l2ll22C. The 7-nitrobenzimidazole was hydrogenated in the pres- :nce of PtO catalyst to give the corresponding 7- aminobenzimidazole (l.1g.) m.p. 99IOOC.

Other compounds representative of the present in lention, which can be prepared according to the above-described procedures, include:

7-Amin0-6-chlorol -npropyl-5- trifluoromethylbenzimidazole, m.p. l08l l l.5C. 7-Amino-6-chlorol -isopropyl-5- trifluoromethylbenzimidazole, l36.5l37.5C. 7-Amino-6-chloro-2-isopropyl-5- trifluoromethylbenzimidazole, l59.5l60.5C. 7-Amino-l-sec-butyl-6-chloro-5- trif'luoromethylbenzimidazole, l2l .5l22.5C. 6,7-Diamino-l-ethyl-Z-methyl-S- trifluoromethylbenzimidazole, m.p. l89.5192C. 'i-Methylamino-l-ethyl-2-methyl-6-methoxy-5- trifluoromethylbcnzimidazole, m.p. lO9-l 105C. 7 Amino-6-ehloro-l-eyclopropyl-2-methyl-5- trifluoromethylbenzimidazole, m.p. l97-20IC. 7-Amino-6-chlorol -isopropyl-2-n-propyl-5- trifluoromethylbenzimidazole, m.p. I06l [4C. 7-Amino-6-chloro-l .2-diisopropyl-5- trifluoromethylbenzimidazole, m.p. l4S-l49C. 7-Amino-6-chloro-l-isopropyl-2-methyl-5- tril'luoromethylbenzimidazole, l58.5l59.5C. 7-Amino-6-chloro-2-ethyl-l-isopropyl-S- trifluoromethylbenzimidazole, m.p. l25l 27C. 7-Amino-fi-ehloro-Z-ethyl-l-n-propyl-S- trifluoromethylbenzimidazole. m.p. l28.5-l30C. 7-Amino-6chloro-2-ethyl-5- trifluoromethylbenzimidazole, llO.5-l l8.5C. 7-Amino'6-chloro-2-isopropyl-l-methyl-5- trifluoromethylbenzimidazole, m.p. l66l68C. 7-Amino-6-ehlor0-2-methyI-5- trifluoromethylbenzimidazole, l35.5l42.5C. 7-Amino-6-chloro-l ,2-diethyl-5 trifluoromethylbenzimidazole. m.p. l63-l64C. 7-Amino-6-chloro-I-ethyl-Z-isopropylfitrifluoromethylbenzimidazole, l50.5l54.5C. 7-Amino-6-chloro l ,2dimethyl-5- trifluoromethylbenzimidazole, m.p. 223228C. 7-Amino-l n-butyl-2-methyl-6-chloro5- tril'luoromethylhenzimidazole, m.p. l49l50.5C.

I2 7 An1inol isobutyl l-methyl-fi-chloro-S- trifluoromethylbcnzimidazole. m.p. l78-l79C. 7-Amino-l-sec-butyl-Z-methyl-6-chloro-5- trifluoromethylbenzimidazole. m.p. l42l43C. 7-Amino-l-( 3-pentyl)-2methyl-6-chloro5 trifluoromethylbenzimidazole, m.p. l6l.5l62C. 7-Amino-2methyl-5-trifluoromethylbenzimidazole,

m.p. l90.5l9l.5C. 7-Amino-2-isopropyl-5- trif'luoromethylbenzimidazole. m.p. l79-l 80C. 7Amino-6-chloro- 1 -ethyl2-hydroxymethyl- Strifluoromethylbenzimidazole. m.p. I82-I84C. 7-Amino-6-chloro-2-(dimethylamino)- l -isopropyl-5- trifluoromethylbenzimidazole. m.p. 9 l "C. 7-Amino-2-methyllisopropyl-5- trifluoromethylbenzimidazole, m.p. 102C. 7-Amino-6-chloro-l-(2-methoxy-l-methylethyl)-2 methyl-5-trifluoromethylbenzimidazole, m.p. l2ll23C. 7-Amino-l 2-dimethyl6-methoxy-5- trifluoromethylbenzimidazole, m.p. l69l 70C. 7-Amino-l-isopropyl-6-methoxy-2-methyl-5- trifluoromethylbenzimidazole, m.p. l55.5-l57C. 7-Amino-2-chloro-l-ethyl-6-methoxy'5- trifluoromethylbenzimidazole, m.p. l58.5l6lC. 7-Aminol Z-bromoethyl )-6-chloro-2-methyl-5- trifluoromcthylbenzimidazole. m.p. l49.5l52C. 7-Amino-2,6-dichlorol -isopropyl-5- trif'luoromethylbenzimidazole, m.p. l56l 62C.

The compounds of this invention are excellent herbicides and can be applied as both a pre-emergence or a post-emergence treatment; that is, they can be applied to soil in which the weeds will grow or, they can be used to kill or suppress the growth of weeds or to kill or prevent the emergence of seedlings of undesirable plants. Thus, the benzimidazoles can be used to control the growth of weeds by applying a phytotoxic amount of one or more of the active compounds of this invention to the locus to be protected; that is, soil in which the weeds are growing or will grow, or the foliage of the growing plants. When used as a pre-emergenee treatment. the compounds may be incorporated, such as by mixing into the top l-3 inches of soil prior to planting the crop, ifdesired. "Weeds as used herein is meant to include any plant growth which is undesirable.

The compounds are especially useful as postemefgenee herbicides for selectively controlling weeds in the presence of desirable crops. such as corn, wheat, barley, rice and sorghum. Hard-tocontrol weeds such as foxtail. velvetleaf, pigweed, Jimsonweed. teaweed, morning-glory and cocklebur are killed at relatively low rates of application with little or no injury to the crop.

Generally, an application rate of from about 0.2 to about 15 pounds of one or more of the active compounds per acre is effective in controlling plant growth. Preferably. an application rate in the range of from about 0.5 to about 5 pounds per acre is employed. At such rates, the undesirable weeds are killed or stunted with little or no injury to desirable crops.

The following examples illustrate the herbicidal activity of typical compounds of this invention.

EXAMPLE XIX The compounds to be tested were evaluated as both a prc-emergence and postemergencc treatment. Greenhouse flats were planted to soybeans (SB). velvetleal (VL), oats (O) and millet (M) and the flats 13 sprayed on the same day as planting with an ethanol solution of the compound to be tested at a rate of five 14 XIX at a rate ofone pound per acre. The hydrochloride salt was dissolved in water. The results are shown in pounds per acre Table ll.

Another set of flats with the same plants was treated TABI E H after the plants had emerged and were about 1 inch in 5 height. These flats were also sprayed with an ethanol solution of the compound to he tested at a rate of 5 Cotton 5/3 9 pounds per acre. The flats were kept in the greenhouse gss and watered when needed. Twenty-one days after z z 0 treatment. the flats were examined and the plants rated E l for herbicidal activity on a 0 to 9 scale in which 0 =n0 33:12? 3 E1 effect. 5 substantial injury with some kill. and 9 Foxtail 9 so complete kill. The results are shown in Table l. Qy elvctleaf 9 9 TABLE I Activity PRE POST Compound SB VL O M SB VL O M 7amino-6-chloro-l-isopropyl-5-trifluoromethyl- U 5 0 2 5 9 5 9 benzimidazole 7-amino6-chloro-l isopropyl-2-methyl-5-tri- 2 8 5 7 9 9 8 9 fluoromethylhenzimidazole 7-amino-6-chlom-Z-ethyl-l-isopropyl-S-tril l l l 9 9 t l 9 fluoromethylhenzimidazolc 7-amino-6-chloro-l-isopropyl Z-n-propyl-S- 2 l 0 O 2 2 l 2 tril'luoromethylbenzimidazole 7-amino-6-ehloro-Z-isopropyl-l-n-propyl-S- 0 0 (l 0 2 l l l trifluoromelhylbenzimidazole 7-amino-6-chIoro-Z-methyl-l-n-propyl-5- l l U l l i l l trifluoromethylbenzimidazole 7-amino-6-chloro-2-ethyl-5-tril'luoromethyl- U 0 (l 0 0 8 (l 5 bemimidazole 7-amino6-chloro-Z-isopropyl-l-methyl-5-tri- 0 l l 2 5 9 l 8 fluoromethylbenzimidazole 7-amino-6 ehloro Z-methyl-S-trifluoromethyl- (l 0 0 2 l R l 7 benzimidazole 7-amino-6-ehloro-l.Ldicthyl-Sdrifluoro- (l 6 S 5 7 7 5 9 methylhenzimiduzole 7-umino-Lsec hutyl-b-chloro-S-tril'luoro- 0 ll 0 0 0 ll 0 7 h.7-diamino-l-ethylZ-rnethyl-S-tritluoro- 0 (l U (l l 8 0 5 methylhenzimidazole 7-amino-l-cthyl-'l-mcthyl-h-methoxy-S-tri 9 9 9 9 9 8 9 9 fluoromethylhenzimidazole 7 methy|amino lelhyl-2-methyl-6-ehloro 5 0 l 8 9 8 5 9 5-tri['luoromethylhcnlimidazole 7-methylamino-l-ethyl-2 methyl-6-methoxy- 9 6 6 9 9 9 8 9 S-trifluoromethylbenzimidazole 7-amino-l-elhyl-2-methyl-6-dimethylamino-5- 8 B 6 8 7 9 8 9 trifluorumethylhcnzimidaznle 7-methylamino-l-ethyl-Z-methyl-S-trifluoro- 2 9 6 9 5 9 6 9 methylhenzimidazole 7-amino4-ehloro-l-ethyl-fi-methoxy-Z-methyl 0 0 t) (l 5 6 6 7 5'trilluornmethylbenzimidavole 7-amino--1.6-dichloro-lethyl-Z-methyl-$-tri l l l l 7 8 Z 7 l'luoromethylbenzimidazole lamino-h-ehloro-l.Z-dimethyl-S-trilluon l 8 6 9 8 7 R 9 methylhenzimidazole 7-amino-h-chloro-l-l l-methyl-2-n\ethoxyethyll-Z- 3 8 2 l 9 9 7 8 melhyLS-tril'luoromethylhenzimidazole Taminwh-chloro-l-lZ-hromoethyll-I-methylll 0 (l 0 6 9 l 8 5-trifluoromcthylhenzimidazole 7-aniino-h chlorol -l lhydroxyethyl)5-lril'luoro 5 S 7 7 9 9 l 8 methylbemimidazole 7-amino-2.fidiehlorwl-isopropyl-5-tri 2 2 0 l) 6 9 7 9 l'luoromethylbenzimidamle 7-amino-l .2-dimcthyl-6-methoxy-S-trifluom- 8 7 7 7 9 B 8 ll mcthylhemimidaznle 7-amino-l-isopropyl-6-methoxy-2-methyl-S- 9 9 9 9 9 9 8 9 trifluoromelhylhenzimidazole 7-amino-2-chloro-l-ethyHv-methnxy-Sari 2 K 7 8 8 8 7 9 fluuromethylhenzimidalole 7amino'6-chlnro-l-ethyl-2-(hydroxymethyll U 7 0 (l 6 9 t) l) S-trilluoromethylhenwimidarole 7-amimvfi-chluro-Z-tdimethylaminnl-l elhyl 5 (l l) l) U U 8 S 9 tril'luonlmethylhenzimidzmIle 7-amino6-chloro- -isopropyl-2-l dimethyl- 0 0 U 0 l 5 2 7 aminol-5-tnt'luoromethylhenzitnidazole EXAMPLE XX Millet 9 q Peanuts 5/3 2 v Pigwced 9 9 7-Amlno-l-ethyl-7-mcthyLfi-ehloro-S- Jimmnwccd 7/3 8 tr1fluoromethylbenzimidazole was evaluated as a post- 65 leaweed (Prickly Sldu) 6/4 8/4 emergence treatment on a broad class of representative z' -T 7/3 ornlng-glory 9 9 crops and weeds. The compound and its hydrochloride smghum 1 salt were tested according to the procedure of Example Ri In Table 11, where there are two numbers. i.e. 7/3. the TABLE Ill-continued first is percent kill on a 5-9 scale and the second is a Achy/m percent injury to remaining plants on a ()4 scale. Thus, Plant Lmpd. A (m tt B im a, ('mpd l) 5 Mustard 9 8/} ll Johnsongrass I I 1 Cockl -hur 9 9 no efl'cct 2sw; kill 1 1 111 n ury 6 2 1 (ompound A TammoI-eth l-l-isoproml-h chloro-fi I 111*4119'1 thy-i 7 Z 'f 1" tritluonmielh lhen/lnHda/rile 3 4l|-7U/r n ury X 75-99% kill ('ompound 1i TanninIwill lI-mutl\ Hvhromo 4 709; injury '4 I COI PlEKL kl H) lntluoromelh lhen/inilda/ole EXAMPLE XXI Three compounds of the present invention and a known position isomer were tested as post-emergence herbicides at a rate of one pound per acre on a group of representative crops and weeds. The procedure of Example XX was followed. The results were as shown in Table 111.

The examples in Table 111 show the unexpected superiority of the compounds of the present invention having 7-amino and S-trifluoromethyl substituents when compared with the known o-amino isomer. See British Patent No. 1.111905 (French Patent No. 1482.315; (hem/Cal Abstracts 68. 1U1597b [1968]). The 7- amino-substituted compounds are especially against the hard-to-control weeds cockleburi leaf.

useful velvetteaweed, morning-glory. jimsonweed and pig- WC TABLE 111 ed Activity Plant Cmpd. A Cmpd. u Cm d. c Cmpd. o EXAMPLE; XXI] (Zorn l 0 U 1 ma 4 Additional compounds were tested as a post at i Baricy 5/3 5/2 5/3 emergence herbicide at a rate of l or .75 pound per Velvctlcuf 6/2 /3 acre on a group of representative crops and weeds ac Cotton U 9 9 5/2 Mmning g|my 9 9 9 I cording to the procedure of bxamples XX and XXI. Jimsonweed 5/2 8/3 9 5/3 The results were as set forth in Table IV.

TABLE 1V Activity Plant Cmpd. r; Lmpd F (mpdl o Cmpd w (.mpd, 1*

Alfalfa 0 (1 6/1 Cotton 3 1 6/2 9 9 Soybeans 1 1 9 3 Peanuts (1 t) t] 3 2 (orn 1 (1 O 1 1 Wheat 1 2 (J 2 1 Rice 0 U 2 3 2 Field beans 2 11 5/2 Velvctleaf 9 8/1 8/2 9 9 Pigweed 9 3/4 9 9 9 Jimsonwecd 9 8/2 6/1 Tcaweed 8/3 6/2 9 9 9 Morning-glor 2 7/2 8/2 9 9 Foxtail 5/2 5/2 7/3 9 8/1 Walergrass 7/2 6/1 8/2 9 8/2 Mustard 9 9 9 9 9 Ragweed 5/2 fi/Z 6/2 9 9 Wildoats 2 6/2 8/3 6/3 7/3 Sickle-pod 9 3/4 Purslane 9 9 Scsbania 8/2 9 lronweed 9 9 Lambsquarters 9 9 Groundcherry 9 9 Cockle-bur 9 9 Crabgrass 9 9 Sandhur i 7/1 7/2 Johnsongrass 8/4 5/] applied al I) '5 pound per acre Compound [1 7 ufiilnn b-Lhltiro 1-t|ttllcl1i)ldmlntl:-ftl\3lh)l'fi-lrlrlllufllmlflll)Ihen/tmldnlivll: Pompound 1 I 7 .lflilnlt h lihlltfl 1'1I-ntUlhUiQd'l'l'lclhjvlk'lhyll l methyl filrlt'luoromclh lhervlnildmole (ompound (i 'l-timinol.h-dnghloro l L'lh}I-S ltli ltlllfllltltflh}lIWeII/ilttidtllnlu Compound 11 T'dfllllltlfi Litlflrli-|'hUpYUpyl-z-ltlcll'lyl-s\fll lHllHkl'HQlh)lhCn/tlTllLlAt/UIU ompoundj wanono l-nlclltyl l-I\I\|JIUP}1'-H|| |\H\H\mcll\)lhrttllIUlLld/Ulc 1 1 3 3 1/ Since a relatively small amount of one or more of the lcaweed 2 8/4 9 5/1 6S l pigwwd g t, 1 active benzimidazoles should be uniformly distributed l oxlall 8/4 7/3 6/3 H over the area to he treated, the compounds preferable 12128321 1? f are formulated with conventional herbicide carriers. Crabgrass so 1) either liquid or solid. Thus, the compounds can be im pregnated on or admixed with a pulverulent solid carrier such as lime, talc, clay, Bentonite, calcium chloride, vermiculite, and the like. Alternatively, the compounds can be dissolved or suspended in a liquid carrier such as water. kerosene, alcohols, diesel oil. xylene. benzene, glycols, ketones, and the like. Since many of the compounds will form water-soluble salts such as with mineral acids, they can be formulated with water.

A surfactant is preferably included to aid in dispersion, emulsification and coverage. The surfactant can be ionic or nonionic, and may be liquid or a solid. The use of the term surfactant" herein is intended to include such compounds commonly referred to as wetting agents, dispersing agents and emulsifying agents. Typical surfactants include the alkylarylsulfonates, the fatty alcohol sulfates, sodium salt of napthalenesulfonic acid, alkylaryl polyether alcohols, long chain quaternary ammonium compounds, sodium salts of petroleum-derived alkylsulfonic acids, polyoxyethylenesorbitan monolaurate, and the like. These dispersing and wetting agents are sold under numerous trademarks and may either be pure compounds, mixtures of compounds of the same general group, or they can be mixtures of compounds of different classes. Surfactants can also be included in compositions containing a solid inert carrier.

Concentrated compositions containing the active agent which can be subsequently diluted, as with water, to the desired concentration for application to plants and soil are also provided. The advantages of such concentrates are that they are prepared by the manufacturer in a form such that the user need only mix them with a locally available carrier, preferably water, thereby keeping shipping costs to a minimum while providing a product which can be used with a minimum of equipment and effort. Such concentrates may contain from about to about 95 percent by weight ofone or more of the active benzimidazoles with a carrier or diluent, which may be a liquid or a solid. Liquid carriers which are miscible with the active agent or other liquids in which the compound may be suspended or dispersed. can he used. A surfactant is also generally included to facilitate such dilution or dispersion in water. However, the surfactant itself may comprise the carrier in such concentrates.

The herbicidal compositions can include other beneficial adjuvants, such as humectants, oils and contact agents. Further, other herbicides such as the chlorophenoxyacetic acids, substituted uracils and ureas, triazines, dinitroanilines, carbamates, I ,3 phenylenediamines, anilides, amides, and halo alkanoic acids. can be included in the formulation, if desired.

Various changes and modifications of the invention can be made, and, to the extent that such variations incorporate the spirit of this invention, they are intended to be included within the scope of the appended claims.

What is claimed is:

l. A compound of the formula 4 CF 0 \C R x 2 and in which not more than one of said R and R represents hydrogen and not more than one of said X and X represents 2. A compound in accordance with claim I in which R R represents a total of about 2 to 6 carbon atoms.

3. A compound in accordance with claim 1 in which R. and R are lower alkyl.

4. A compound in accordance with claim l in which X, is hydrogen and X is chloro.

S. A compound in accordance with claim 1 in which both R s in the 7-amino group are hydrogen.

6. A compound in accordance with claim 1 in its hydrochloride salt form.

7. A compound in accordance with claim I in which R is chloro.

8. 7-Aminol -ethyl-2-methyl-5- trifluoromethylbenzimidazole.

9. 7-Amino-6-chloro-l-ethyl-2-methyl-5- trifluoromethylbenzimidazole.

l0. 7-Amino-6-methoxy-l -ethyl-2-methyl-5- trifluoromethylbenzimidazole.

ll. 7-Amino-6-chloro-l -isopropyl-2-methyl-5 trifluoromethylbenzimidazole.

l2. 7-Amino-l -isopropyl-2-methyl-S- trifluoromethylbenzimidazole.

13. The compound in accordance with claim I, 7- amino-2,6-dichlorol -isopropyl-5- trifluoromethylbenzimidazole.

l4. The compound in accordance with claim I, 7- arninol -isopropyl-6-methoxy-2-methyl-5- trifluoromethylbenzimidazole.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,901,910 DATED August 26, 1975 INVENTORtS) I D.L. Hunter, R.A. Smith and w.s. Belles H is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown betow:

In Column t, lines 2 6 delete Cl /R c: C1 C]. R

and add R Cl /C: Cl

In Column 10, line 23 delete "1A2 c." and add --l r2.5c.--

In Column 13, line 55 in TABLE I for the compound, T-amino-6- chloro-l-ethyl-2-(hydroxymethyl?-5-tr'ifluoromethylbenzirnidazole, under the SB heading, delete "6 and add O Signcd and Scaled this A ttest:

RUTH C. MASON C. M Arresting Offi ARSHALL DANN ummrssr'mwr uj'later'rrs and Trademarks 

1. A COMPOUND OF THE FORMULA
 2. A compound in accordance with claim 1 in which R1 + R2 represents a total of about 2 to 6 carbon atoms.
 3. A compound in accordance with claim 1 in which R1 and R2 are lower alkyl.
 4. A compound in accordance with claim 1 in which X4 is hydrogen and X6 is chloro.
 5. A compound in accordance with claim 1 in which both R3''s in the 7-amino group are hydrogen.
 6. A compound in accordance with claim 1 in its hydrochloride salt form.
 7. A compound in accordance with claim 1 in which R2 is chloro.
 8. 7-Amino-1-ethyl-2-methyl-5-trifluoromethylbenzimidazole.
 9. 7-Amino-6-chloro-1-ethyl-2-methyl-5-trifluoromethylbenzimidazole.
 10. 7-Amino-6-methoxy-1-ethyl-2-methyl-5-trifluoromethylbenzimidazole.
 11. 7-Amino-6-chloro-1-isopropyl-2-methyl-5-trifluoromethylbenzimidazole.
 12. 7-Amino-1-isopropyl-2-methyl-5-trifluoromethylbenzimidazole.
 13. The compound in accordance with claim 1, 7-amino-2,6-dichloro-1-isopropyl-5-trifluoromethylbenzimidazole.
 14. The compound in accordance with claim 1, 7-amino-1-isopropyl-6-methoxy-2-methyl-5-trifluoromethylbenzimidazole. 